WASHINGTON—At the AUVSI Unmanned Systems conference, New Mexico-based startup Titan Aerospace unveiled the company's prototypes for "atmospheric satellites"—autonomous unmanned aircraft powered purely by solar energy and capable of staying aloft at high altitude for up to five years. The first commercially manufactured long-endurance solar drone, the Solara 50, is under construction now and is expected to fly next year. A bigger drone, the Solara 60, will soon follow.

While solar-powered flight has been a reality since the early 1980s, Titan is the first company to work on commercially manufacturing solar-powered drones. And unlike some of the prototypes that have been flown by the established players in the aerospace and unmanned systems field, the Solara drones are based on well-worn technologies and simplicity in design.

If successful, Titan could change the economics of businesses that have previously depended on low-orbit satellites and allow for a persistent coverage closer to what satellites in geostationary orbit provide.

On the wings of a penguin

Solar-powered flight has been a reality since AeroVironment took the lessons from the human-powered aircraft Gossamer Albatross—which flew across the English Channel in 1979—and applied them in the Gossamer Penguin and Solar Challenger aircraft in the early 1980s. But complexity and durability issues have dogged most efforts to create the holy grail of solar aircraft—a drone that can stay aloft indefinitely.

AeroVironment has built a number of solar-powered aircraft for the government, including the Helios prototype—a giant drone with a wingspan of 247 feet powered by solar panels and hydrogen fuel cells. The Helios crashed off of Hawaii in 2003 when it suffered structural failure due to turbulence.

The early success of Helios partially inspired the Defense Advanced Research Projects Agency (DARPA) and Boeing's "Vulture" program in 2008, an effort to create a drone that could spend up to five years on station at 60,000 to 90,000 feet with a thousand-pound payload. Qinetq's Zephyr, one of the program's competitors, flew for 336 hours and 22 minutes, setting the endurance record for unmanned aircraft—but it set the record after DARPA cut the funding for the Boeing contract and reduced the program's scope to work on solar cells and energy storage systems.

That didn't end the Defense Department's appetite for long-flying drones. But the alternative paths chosen so far haven’t paid off. Another AeroVironment aircraft, the Global Observer—a purely hydrogen-powered drone with a 70-foot wingspan designed for week-long missions—crashed in 2011, resulting in the termination of the program by the Pentagon. Boeing has its own hydrogen-powered, long-endurance drone, the Phantom Eye, in development; so far its longest flight has been just over two hours.

A model of Boeing's Phantom Eye at Boeing's AUVSA conference booth.

Almost orbital

Titan's aircraft plans are more modest and much more ambitious at the same time. Solara 50 will have a payload of just 70 pounds—though depending on the time of year and location of the flight, longer daylight hours could sustain flights with heavier payloads. The next design, the Solara 60, will carry up to 250 pounds. Instead of using hydrogen fuel cells, the Solara aircraft use batteries charged from solar panels to power flight at night and provide about 100 watts of power to the aircraft's payload, as well.

The Solara 50 has a 50 m (164 feet) wingspan. The upper surfaces of its wings and tail are packed with over 3,000 photovoltaic cells capable of generating up to 7 kilowatts. It is launched by catapult and can land (when it has to) by skidding on its Kevlar-coated underside. Unlike the giant flying-wing configurations of the Helios and Zephyr, which had large numbers of propellers, the Solara has a single, high-efficiency motor.

In theory, a solar-powered drone capable of withstanding long flights at high altitude—in what Titan executives call the "sweet spot" in the Earth's atmosphere between 60,000 and 70,000 feet, above nearly all weather patterns in a zone where winds are typically less than 5 knots (5.75 miles/hour)—would be able to perform tasks usually reserved for satellites at a much lower cost.

For example, during a presentation by Titan at AVUSA, a company spokesperson compared using a satellite for multispectral Earth imagery—say, like Landsat's—to using an atmospheric satellite. A drone could be put up quickly, for much less initial capital. At the same time, it would provide targeted imagery at a cost of less than $5 per square kilometer—versus $35 per square kilometer from a satellite—while still offering the large area of coverage of a satellite.

Enlarge/ The coverage area of a Solara 50, superimposed over New York.

As a communications relay, the Solara offers about an 18-mile radius of coverage—easily covering all of New York City's five boroughs, as shown in the map above. A "constellation" of Solara craft could create a persistent communication network for disaster relief efforts or could provide long-term services.

Titan already has customer reservations for the first three of its Solara drones, two of which are intended to serve as communications relays (though the customer has not been identified). The first will be delivered in February, with manufacturing ramping up for monthly delivery starting in April.

55 Reader Comments

Very cool. This opens up a lot of options for communications in areas without good ground based cell coverage, without the latency of a proper satellite link (the speed of light to orbit is still a major problem). A few of these could easily relay data down to a ground based mesh without the mesh having to connect out to the internet over the ground.

It gives you more control over the location of each drone, but at the cost of dramatically increased complexity (and likely cost). The balloons are likely more useful for general area coverage ("I want to cover a country cheaply"), and the drones are more likely useful for spot coverage ("I need communication in place over a disaster area.") I think the ideas complement each other quite well.

Obviously this will be subject to seeing how they work in actual deployment, but I don't think either one is an unworkable concept.

I always love it when writers make statements like "can fly five years without landing". Really? How many of these five-year flights has the device made so far? Engineering pipe dreams sometimes, but rarely, come true and speaking of flight duration for a machine which doesn't exist means nothing. I can just as readily claim that my secret invisible anti-gravity flying saucer can fly to Proxima Centauri and back in three days without refueling but until I do it, it is just a gassy statement. Please, when a company makes extravagant claims for untested technology, show just a bit of skepticism.

The projected payload capacity of 70 lbs is actually better than I expected, but the other half of that question is what is the power envelope? If you have to provide your own power then 70 lbs is not much at all.

Given the previous history of long-duration drone flight, I'd want a bit more proof from the company before buying if I was a potential customer, but even if it only lasts a year instead of 5 years then the potential uses are really amazing.

I always love it when writers make statements like "can fly five years without landing". Really? How many of these five-year flights has the device made so far? Engineering pipe dreams sometimes, but rarely, come true and speaking of flight duration for a machine which doesn't exist means nothing. I can just as readily claim that my secret invisible anti-gravity flying saucer can fly to Proxima Centauri and back in three days without refueling but until I do it, it is just a gassy statement. Please, when a company makes extravagant claims for untested technology, show just a bit of skepticism.

I imagine these claims are based on the quality of materials used and the stability of the operating environment. An electric motor that runs for years on end is not an exotic beast. For example I run my upstairs HVAC fan constantly.

Further, we've got a lot of experience with photovoltaic and airframe longevity - and 5 years doesn't seem all that exotic or unbelievable. Sure the PV cells will degrade, as will the batteries. I imagine they've modeled and accounted for that. I bet that's why the lifetime is 5 years, rather than 10.

The projected payload capacity of 70 lbs is actually better than I expected, but the other half of that question is what is the power envelope? If you have to provide your own power then 70 lbs is not much at all.

Given the previous history of long-duration drone flight, I'd want a bit more proof from the company before buying if I was a potential customer, but even if it only lasts a year instead of 5 years then the potential uses are really amazing.

The projected payload capacity of 70 lbs is actually better than I expected, but the other half of that question is what is the power envelope? If you have to provide your own power then 70 lbs is not much at all.

Given the previous history of long-duration drone flight, I'd want a bit more proof from the company before buying if I was a potential customer, but even if it only lasts a year instead of 5 years then the potential uses are really amazing.

It really doesn't seem like it should be a problem. These things fly high enough that the photovoltaics should be pretty efficient (on par with the systems on satellites). We've got a lot of experience running communications links using satellite-quality photovoltaics/batteries.

The early comments are optimistic about the neat technological achievements.

My first thoughts drifted toward the notion of private/corporate drone surveillance. They were not happy thoughts.

Right now, technical limitations help prevent wider spread massive violations of privacy. Only unlimited-budget organizations like DOD or NSA can have such capabilities. And they haven't exactly been wielding their powers responsibly lately.

What will it mean when Virgin or Verizon or WalMart can afford a fleet of observation drones?

Pretty cool, something like that could be used to monitor wildlife and other neat applications. The obvious law enforcement/military/private corporations uses will likely happen regardless of what we say about it though. This kind of UAV could be also used for escorting/monitoring cargo ships to provide advance warning from pirates (Real sea faring ones not the internet kind)

Once their company is more established, I wonder if they could shift to a different model of business. Rather than just selling the SOLARA to customers, they could outfit some with a payload that is common to most of their customers, and then launch them. They could then monitor different areas of the planet with them and, then just sell the information instead of selling the aircraft.

I always love it when writers make statements like "can fly five years without landing". Really? How many of these five-year flights has the device made so far? Engineering pipe dreams sometimes, but rarely, come true and speaking of flight duration for a machine which doesn't exist means nothing.

They're going into commercial production within months, and have customers signed up. Call me an optimist, but I'm guessing they've likely actually done a fair bit of testing, and are more than just blowing pipe-dream smoke.

I always love it when writers make statements like "can fly five years without landing". Really? How many of these five-year flights has the device made so far? Engineering pipe dreams sometimes, but rarely, come true and speaking of flight duration for a machine which doesn't exist means nothing.

They're going into commercial production within months, and have customers signed up. Call me an optimist, but I'm guessing they've likely actually done a fair bit of testing, and are more than just blowing pipe-dream smoke.

But enlighten us, which area of their design strikes you as flawed?

Qinetq's Zephyr, one of the program's competitors, flew for 336 hours and 22 minutes, setting the endurance record for unmanned aircraft - from the article... 337hrs is quite a bit less than 43800hrs

Presumably this thing is launched by some sort of catapult, being landing-gear-less (hence the belly-skid touchdown). This seems like a point where you could further optimise for long-duration high-altitude flight: staging. Use a dedicated craft to take off, climb and accelerate to altitude, and then release a much lighter, structurally weaker craft that only has to deal with sustaining speed at altitude, with no worries about having to endure catapult acceleration or landing shocks. When you need to bring it down for maintenance, send the carrier up again to snag it and retrieve it (even delivering it's replacement on the same flight). You could have a constellation of cheaper drones tended to by only a handful of carrier craft.

I always love it when writers make statements like "can fly five years without landing". Really? How many of these five-year flights has the device made so far? Engineering pipe dreams sometimes, but rarely, come true and speaking of flight duration for a machine which doesn't exist means nothing.

They're going into commercial production within months, and have customers signed up. Call me an optimist, but I'm guessing they've likely actually done a fair bit of testing, and are more than just blowing pipe-dream smoke.

But enlighten us, which area of their design strikes you as flawed?

Qinetq's Zephyr, one of the program's competitors, flew for 336 hours and 22 minutes, setting the endurance record for unmanned aircraft - from the article... 337hrs is quite a bit less than 43800hrs

It also sounds like sufficient data to be able to make a reasonably accurate estimation of 5 years operating time. That is, by looking at what caused it to stop after 336 hours, you know how much wear-and-tear such a device gets long-term, and can therefore estimate what you need to do to ensure it survives long-term.

Back in the early 1990s I briefly worked for a company that was making UAVs. They were planning on moving from Maryland to Texas, largely due to liability (I'm pretty sure it was due more to population density than different laws). While I realize that an unpowered/uncontrolled decent from above the center of the example circle over New York City should fall in the Atlantic (prevailing Western winds and all), I wonder just how confident their insurance company is (then there are issues with self destruct sequences and all)*.

* note that this isn't remotely a terrorist threat (at least with sane programming). A "cyberwarrior" might think that blowing up an "air satellite" is more impressive than just taking down a website and eventually find the means to send the signal.

I always love it when writers make statements like "can fly five years without landing". Really? How many of these five-year flights has the device made so far? Engineering pipe dreams sometimes, but rarely, come true and speaking of flight duration for a machine which doesn't exist means nothing.

They're going into commercial production within months, and have customers signed up. Call me an optimist, but I'm guessing they've likely actually done a fair bit of testing, and are more than just blowing pipe-dream smoke.

But enlighten us, which area of their design strikes you as flawed?

What I was asking for was a bit of realism in the writing. Had the headline read something like "claimed, based on design calculations, that the aircraft might stay aloft for five years" rather than the bald statement that it would, would have made me happier. As for the engineering shortcomings it probably falls into the same category as every other bleeding-edge design in that every component must perform flawlessly at state-of-the-art levels for the entire run period -- any slacking off by any single component would truncate the flight. One need only look at the ISS to see failures that would mean nothing on Earth becoming critical --- it isn't as if simple liquid/gas couplings or bearings or power cables are new technology but in space no one can hear the engineers scream.

Presumably this thing is launched by some sort of catapult, being landing-gear-less (hence the belly-skid touchdown). This seems like a point where you could further optimise for long-duration high-altitude flight: staging. Use a dedicated craft to take off, climb and accelerate to altitude, and then release a much lighter, structurally weaker craft that only has to deal with sustaining speed at altitude, with no worries about having to endure catapult acceleration or landing shocks. When you need to bring it down for maintenance, send the carrier up again to snag it and retrieve it (even delivering it's replacement on the same flight). You could have a constellation of cheaper drones tended to by only a handful of carrier craft.

I'm not sure about this. Obviously you couldn't fit a 50m wingspan drone into any conventional (or unconventional) aircraft, so you'd have to carry it outside the carrier craft and expose the drone to whatever forces the carrier goes through when climbing up. Or introduce unnecessary structural weakness by folding the wings. Furthermore, the drone probably requires considerably less speed to take off than any carrier aircraft would, so the catapult might actually be more gentle than accelerating with some jet. Maybe a balloon or something that can easily reach high altitudes, I don't know. Doesn't sound feasible to a layman.

The weather service puts up a balloon every day from every station to atmospheric data. I guess something like this could be constantly in the air above the station with a constantly changing altitude in order to collect the data previously captured by the balloons. I guess the problem would be that this isn't designed to work in lower atmosphere weather and when damaged, it will be far more expensive to replace than a balloon. Although, I'm sure something like this could supplement the balloons. I hope this device lives up to it's promise.

I support ARSBodger on more skepticism. Maybe they have all their ducks in a row, but the flight record hasn't been that impressive so far. I do love that they are trying.

My nitpick with the article is "almost orbital". From a scale of 1 to 10 where 1 is on the ground and 10 is in-orbit, these solar powered drones are like 0.1, maybe a 0.01. These drones go about 100 to 300 mph or so? Probably even slower. You need to be going about 15,000 mph to reach a stable orbit. So the velocity is about 2 orders of magnitude off with these drones. That's a rather imaginative definition of "almost orbital".

My take: any drone not specially launched to deal with a specific, temporary situation MUST BE DESTROYED. And if you can't figure out why someone might have that idea, then you deserve what's about to happen (24/7 physical surveillance).

I support ARSBodger on more skepticism. Maybe they have all their ducks in a row, but the flight record hasn't been that impressive so far. I do love that they are trying.

My nitpick with the article is "almost orbital". From a scale of 1 to 10 where 1 is on the ground and 10 is in-orbit, these solar powered drones are like 0.1, maybe a 0.01. These drones go about 100 to 300 mph or so? Probably even slower. You need to be going about 15,000 mph to reach a stable orbit. So the velocity is about 2 orders of magnitude off with these drones. That's a rather imaginative definition of "almost orbital".

I don't think they are using your definition of 'orbital'. I think they mean how high it flies. And the ability to provide similar services to a geosynchronous orbital satellite for a local area.

Sean Gallagher / Sean is Ars Technica's IT Editor. A former Navy officer, systems administrator, and network systems integrator with 20 years of IT journalism experience, he lives and works in Baltimore, Maryland.